<template>
    <el-select v-model="valueTitle" :value="valueTitle" :clearable="clearable" @clear="clearHandle" placeholder="请选择所属目录" :disabled="!clickable">
        <el-option :value="valueTitle" :label="valueTitle" class="options">
            <el-tree
                id="tree-option"
                ref="selectTree"
                :accordion="accordion"
                :data="options"
                :props="props"
                :node-key="props.value"
                :default-expanded-keys="defaultExpandedKey"
                @node-click="handleNodeClick">
            </el-tree>
        </el-option>
    </el-select>
</template>

<script>
export default {
    name: "el-select-tree",
    props: {

        // el-tree配置项，挺离谱的，关键字长tm一样
        props: {
            type: Object,
            default: () => {
                return {
                    value: 'id',             // ID字段名
                    label: 'title',         // 显示名称
                    children: 'children'    // 子级字段名
                }
            }
        },

        // 选项列表数据(树形结构的对象数组)
        options: {type: Array, default: () => []},

        // 初始值
        value: {type: String, default: null},

        // 可清空选项
        clearable: {type: Boolean, default: true},

        // 自动收起
        accordion: {type: Boolean, default: false},

        // 可点击
        clickable: {type: Boolean, default: false}
    },
    data() {
        return {
            valueId: null,
            valueTitle: '',
            defaultExpandedKey: []
        }
    },
    mounted() {
        this.valueId = this.value    // 初始值
        this.initHandle()
    },
    methods: {
        // 初始化值
        initHandle() {
            console.log('selecttree-initHandle->options:')
            console.log(this.options)
            if (this.valueId) {
                if (this.valueId !== '0') {
                    console.log('selecttree-initHandle->valueId:')
                    console.log(this.valueId)
                    console.log('selecttree-initHandle->selectTree:')
                    console.log(this.$refs.selectTree.getNode())
                    this.valueTitle = this.$refs.selectTree.getNode(this.valueId).data[this.props.label]     // 初始化显示
                    this.$refs.selectTree.setCurrentKey(this.valueId)       // 设置默认选中
                    this.defaultExpandedKey = [this.valueId]      // 设置默认展开
                } else {
                    this.valueTitle = ''
                }
            }
            this.initScroll()
        },

        // 初始化滚动条
        initScroll() {
            this.$nextTick(() => {
                let scrollWrap = document.querySelectorAll('.el-scrollbar .el-select-dropdown__wrap')[0]
                let scrollBar = document.querySelectorAll('.el-scrollbar .el-scrollbar__bar')
                scrollWrap.style.cssText = 'margin: 0px; max-height: none; overflow: hidden;'
                scrollBar.forEach(ele => ele.style.width = 0)
            })
        },

        // 切换选项
        handleNodeClick(node) {
            console.log('node: ' + node)
            this.valueTitle = node[this.props.label]
            this.valueId = node[this.props.value]
            this.$emit('getValue', this.valueId)
            this.defaultExpandedKey = []
        },

        // 清除选中
        clearHandle() {
            this.valueTitle = ''
            this.valueId = null
            this.defaultExpandedKey = []
            this.clearSelected()
            this.$emit('getValue', null)
        },

        // 清空选中样式
        clearSelected() {
            let allNode = document.querySelectorAll('#tree-option .el-tree-node')
            allNode.forEach((element) => element.classList.remove('is-current'))
        }

    },

    watch: {
        value() {
            this.valueId = this.value
            this.initHandle()
        }
    },
}
</script>

<style scoped>
.el-scrollbar .el-scrollbar__view .el-select-dropdown__item {
    height: auto;
    max-height: 274px;
    padding: 0;
    overflow: hidden;
    overflow-y: auto;
}

.el-select-dropdown__item.selected {
    font-weight: normal;
}

ul li >>> .el-tree .el-tree-node__content {
    height: auto;
    padding: 0 20px;
}

.el-tree-node__label {
    font-weight: normal;
}

.el-tree >>> .is-current .el-tree-node__label {
    color: #409EFF;
    font-weight: 700;
}

.el-tree >>> .is-current .el-tree-node__children .el-tree-node__label {
    color: #606266;
    font-weight: normal;
}
</style>
